This dissertation set out to examine whether a relationship existed between ideas of race and great power politics, specifically as it influenced the perceptions of key American and British political leaders towards each other and Germany, during the late 19th and early 20th centuries. It examines private correspondence, key public statements, and contemporary publications, analyzing where theories and fears regarding race influenced the thinking of key individuals during critical international incidents. The dissertation uses a model to conceptualize race as seen by contemporary leaders that incorporates both biological and cultural elements. From here, it furthermore proposes that it is indeed possible to identify at least certain key moments when breaks occurred between Anglo-Saxon and a broader conceptualization of Teuton to political leaders. It first examines contemporary thought on race as seen by these leaders, looks at specific crises in the Americas, Africa, and Asia, and concludes with an analysis of how race impacted views on contemporary immigration to the United States and the process of amalgamation between races. Moreover, it reveals that the weighting of the cultural and biological elements shifted, moving from viewing race as Anglo-Saxon to the paradigm of the English-speaking races. The dissertation highlights that especially during the Presidency of Theodore Roosevelt, race indeed increasingly influenced the thinking of the United States and Britain with respect to foreign policy, especially through concerns of migration and settlement, and created a perception of seemingly disproportionate threat from Germany. In doing so, the United States and settler colonies became of paramount importance in this rivalry with Germany, in part due to their ability to turn migrants from Europe into members of the English-speaking race.